As is well known in the art of raising swine, animal shelters in the form of farrowing houses are typically used in which parallel rows of farrowing crates are supported on respective concrete floor sections known as "gang slats." Each such gang slat is of an overall width about equal to the width of a farrowing crate supported thereon, and each farrowing crate has a central pen for confining a sow therein and side pens extending along opposite sides of the central pen for accommodating a litter of pigs. The litter has access to the sow for feeding by passing under a divider extending between the central pen and each side pen.
For some time, it has been the usual practice to utilize elongate gang slats having a plurality of longitudinally extending slots therein for passage therethrough of waste from the sow and the litter of pigs in the respective farrowing crate to a pit therebelow. The slotted gang slats thus reduce cleaning and also greatly retard the spread of disease and parasites by allowing removing of animal waste from the farrowing crates. Also, the slotted floor formed of the gang slats is an essential component in controlling the atmospheric environment of the farrowing house, in that air circulates downwardly through the slots to control the temperature and the diffusion of odors.
Known gang slats, such as those discussed above, generally have included a slotted central section of reinforced concrete for supporting the sow in the central pen of a farrowing crate thereon, and they have also included slotted opposing side sections of reinforced concrete, integral with the central section, for supporting the farrowing crate side pens and the litter of pigs thereon. Most of the slots in the gang slat are relatively narrow and thus have presented only a minimal hazard to the safety of the pigs in the litter. However, in order to permit the sow's waste to more readily pass through the gang slat to the pit below, each gang slat has been provided with a group of relatively wider slots in a rear portion of the central section of the gang slat. Since such wider slots usually have been about one inch (25.4 mm) wide, it can be appreciated that the feet and legs of newborn pigs would easily be caught in such relatively wide slots and this would result in serious injury or even death to the pigs. This problem is avoided according to the invention in said copending application by providing a gang slat whose rear portion has an opening therein in which a grate means is positioned, and wherein the openings in the grate means are sufficiently small so as to permit the litter of pigs to be born thereon and walk thereon without injury as by their feet being caught in the openings of the grate means, and wherein the openings are of sufficient size for readily permitting the sow's and the newborn pigs' waste to pass therethrough.
It has now been determined that, even though the longitudinally extending slots in opposing side sections of the gang slats have been relatively narrow heretofore so that the feet and legs of newborn pigs are not likely to be caught in the slots in such side sections, the skin on the front knees of newborn pigs frequently is abraded during their feeding. The suckling of newborn pigs requires substantial pushing with their hind feet and pivoting of the front knees in attempting to maintain a nipple and at the same time to massage the udder to stimulate milk flow. Since the gang slat is made from concrete, relatively rough or abrasive surfaces are present upon which the front knees of the pigs slide while the pigs are feeding so that the skin on their front knees is abraded. In some instances, such knee abrasions are so severe that the leg bones are actually exposed and may become infected such that the infected pigs are unable to nurse and must be culled from the litter.
Attempts have been made heretofore to reduce the occurrence of such knee abrasions. One such attempt is disclosed, for example, in Arends U.S. Pat. No. 3,884,188, dated May 20, 1975, in which a knee protector pad is used on the floor of a farrowing crate. The pad is provided with spaced-apart longitudinal ridges against which the newborn pigs brace their hind feet while suckling, and during which the front knees of the pigs would be protected by smooth imperforate portions of the pad between, and adjacent opposite sides of, such ridges. While such a pad might serve to aid the newborn pigs in suckling while protecting their front knees, it can be appreciated that frequent cleaning and removal of the pigs' waste from the pad would be required to protect the health of the pigs, since otherwise, excessive waste would accumulate on the smooth imperforate portions of the pad.